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<meta charset="utf-8">
<title>gl.readPixels() test to Wasm Memory 16GB in size.</title>
<link rel="stylesheet" href="../../resources/js-test-style.css"/>
<script src="../../js/js-test-pre.js"></script>
<script src="../../js/webgl-test-utils.js"> </script>
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<body>
<canvas id="canvas" width="2" height="2" style="width: 40px; height: 40px;"></canvas>
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<script>
"use strict";
description(document.title);
debug("");
debug("Tests that readPixels can be called on the end of a WebAssembly Memory of 16GB in size.");
debug("");
let wtu = WebGLTestUtils;
let gl = wtu.create3DContext("canvas", undefined, 2);

const PAGE = 65536;
const SIZE = 16*1024*1024*1024;
(() => {
  let view;
  try {
    view = new Uint8Array(new WebAssembly.Memory({ address: 'i64', initial: BigInt(SIZE / PAGE) }).buffer);
  } catch (e) {
    let fn = e instanceof RangeError ? testPassed : testFailed;
    fn(`Allocating ${SIZE} threw: ${e}`);
    return;
  }

  // Clear the canvas to a specific color
  const expectedColor = [42, 84, 128, 255];
  gl.clearColor(expectedColor[0]/255.0, expectedColor[1]/255.0, expectedColor[2]/255.0, expectedColor[3]/255.0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  // Test that gl.readPixels() can be called with a high offset to Memory
  const offset = SIZE - 4;
  view.set([0,0,0,0], offset); // For good measure, clear data at offset before reading
  try {
    gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, view, offset);
  } catch (e) {
    testFailed(`readPixels from ${view.length} byte view threw: ${e}`);
    return;
  }
  wtu.glErrorShouldBe(gl, gl.NO_ERROR);
  let obtainedColor = view.subarray(offset, offset+4);
  expectArray(obtainedColor, expectedColor);
})();

var successfullyParsed = true;
</script>
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